Question

Your boss asks you to design a room that can be as soundproof as possible and provides you with three samples of material. The only information on each sample's label is the material's coefficient of absorption. The coefficient of absorption listed on Sample A is 30%, on Sample B is 47%, and on Sample C is 62%. When your boss asks for your choice and the reasoning behind it, what would you tell him? A. Sample A would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the largest. B. Sample C would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest. C. Sample A would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest. D. Sample C would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the largest.

Answer 1

Answer : Option B) Sample C would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.

Explanation : To design a soundproof room the best material has to be an excellent sound absorber as compared to other available materials. When judging the materials on the basis of their sample's absorption co-efficient, it is easy to find that sample C has the higher absorption percentage i.e. 62 percent as compared to sample A and sample B which are 30 percent and 47 percent respectively.

Answer 2

The correct answer would be B. Since Sample C has the highest coefficient of absorption, this means that it absorbs more sound waves, leaving a smaller fraction of sound waves to be reflected. The smaller fraction of sound waves means that each "bounce" leaves lesser and lesser sound waves to travel around the room.